Microelectromechanical system (“MEMS”) condenser microphone dies typically have a diaphragm that forms a variable capacitor with an underlying backplate. Receipt of an audio signal causes the diaphragm to vibrate and generate a variable capacitance signal representing the audio signal. This variable capacitance signal can be amplified, recorded, or otherwise transmitted to another electronic device. Such microphones typically are enclosed in a package to shield sensitive microphone components from environmental conditions.
These microphone packages have an aperture that allows acoustic signals to reach the microphone. Undesirably, in addition to allowing access for acoustic signals, the aperture can allow access to contaminants that can compromise microphone operation. For example, particles and moisture can enter the interior of the microphone and interfere with movement of the variable capacitor. Additionally, thermal expansion mismatches between the microphone die and the package materials on which the microphone die is mounted can limit the operating temperature range for these microphone systems. These problems often compromise condenser microphone systems operating in harsh environments having very high-temperatures, radio frequency interference/electromagnetic interference (“RFI”/“EMI”), and high volumes of airborne contaminants such as dirt, dust, and liquids.